Question HAF 700 EVO fan setup

[cameraman]

With a Cooler Master HAF 700 EVO arriving next week I would like to order any additional fans that make sense.

ASUS ROG MAXIMUS Z790 DARK HERO LGA 1700 ATX Gaming Motherboard

iCUE H170i ELITE CAPELLIX XT Liquid CPU Cooler 420mm (140 x 3)

While six 120mm might fit in the top, the 420mm radiator installed on the top limits the top fan configuration to just that.

The bottom is pre-installed with one SickleFlow PWM ARGB 120mm. It makes sense to fill the empty slots with two more.

I'm thinking that should be all I need, the two additional 120mm bottom fans for a good balanced airflow.

There are multiple alternative options to install the CPU cooler radiator. Inside the case for example that would allow six 120mm fans on the top. Other than fun to do, I'm not sure I want to unless there is a functional advantage.

https://coolermaster.egnyte.com/dl/V7O5kGdGgs

Thanks.

 

[Aeacus]

for a good balanced airflow.

So, you want neutral pressure? If so, this is the most difficult to achieve compared to negative and positive pressure.

PC case comes with:
2x 200mm front intake
1x 120mm bottom intake
2x 120mm rear exhaust

And it also depends where you install the rad.
4 possible spots that support 3x 140mm:
front intake
bottom intake
top exhaust
side intake/exhaust

There are many combinations to achieve neutral pressure. E.g

#1
2x 200mm front intake
2x 200mm top exhaust
3x 140mm bottom intake (one spot for rad)
3x 140mm side exhaust (another spot for rad)
no 120mm rear exhaust fans

This way, 200mm fans would balance themselves out and so with 140mm fans. If you keep the 120mm rear exhaust fans, you'll get negative pressure.

#2
3x 140mm front intake (one spot for rad)
3x 140mm top exhaust (another spot for rad)
3x 120mm side exhaust
2x 120mm rear intake (flip the rear fans around)
1x 120mm bottom intake

This way, 140mm fans would balance themselves out. Same with 120mm fans.

And several other combinations.
As i said, neutral pressure is hardest to achieve since you have to balance the fans out, both in numbers and in size.

In general, 2x 140mm ~= 3x 120mm (given that fans have the same CFM and mmH2O).

 

[cameraman]

So, you want neutral pressure? If so, this is the most difficult to achieve compared to negative and positive pressure.

PC case comes with:
2x 200mm front intake
1x 120mm bottom intake
2x 120mm rear exhaust

And it also depends where you install the rad.
4 possible spots that support 3x 140mm:
front intake
bottom intake
top exhaust
side intake/exhaust

There are many combinations to achieve neutral pressure. E.g

#1
2x 200mm front intake
2x 200mm top exhaust
3x 140mm bottom intake (one spot for rad)
3x 140mm side exhaust (another spot for rad)
no 120mm rear exhaust fans

This way, 200mm fans would balance themselves out and so with 140mm fans. If you keep the 120mm rear exhaust fans, you'll get negative pressure.

#2
3x 140mm front intake (one spot for rad)
3x 140mm top exhaust (another spot for rad)
3x 120mm side exhaust
2x 120mm rear intake (flip the rear fans around)
1x 120mm bottom intake

This way, 140mm fans would balance themselves out. Same with 120mm fans.

And several other combinations.
As i said, neutral pressure is hardest to achieve since you have to balance the fans out, both in numbers and in size.

In general, 2x 140mm ~= 3x 120mm (given that fans have the same CFM and mmH2O).

Thats is a very detailed and appreciated response that has me thinking; Is neutral pressure preferred to negative pressure or positive pressure? A Toms article seems to prefer negative pressure vs. positive pressure for cooling. I should have asked what the optimal fan pressure for this case would be for cooling.

What would be the optimal location to install the radiator? I would prefer to keep the pre-installed fans in place and add where needed but am open to configure everything up front in as optimal as practical.

Edit: as I read about pros and cons of case pressure, while negative pressure might be better for cooling, the location I plan for my case can attract dust and a slightly positive pressure might be better in my case, pun intended.

Thanks again for the reply.

 

[Aeacus]

Is neutral pressure preferred to negative pressure or positive pressure?

Depends.

Negative pressure - best cooling, worst dust intake.
Positive pressure - best against dust (if you filter all intakes), worst cooling.
Neutral pressure - between the two.

Most PC cases out there are geared towards negative pressure (more exhaust fan mounts than intake) and i'm also running slight negative pressure inside my systems.

With negative pressure and unless you don't have it extreme (e.g no intake fans), the dust isn't that big of a deal. But since in negative pressure, the air and (dust as well) seeps in from all the gaps and holes the PC case has, there is some dust build-up inside the PC.
E.g in my main build, i have one such spot at the back panel, near the PSU. But since there are only some power cables there, the dust that collects there, doesn't hinder the PC's operation in any way.

So, 1st decide which of the pressure you'd like to have.

If you hook up the fans individually to MoBo or fan controller, then the size and placement of the fans isn't that important, since when you can control individual fan RPM (i have my PCs set up in such a way), then by adjusting the RPM of certain fans, you can freely create: positive, neutral or negative pressure.

E.g in my main build (Skylake, full specs with pics in my sig), i have:
2x 140mm front intake (both individually controlled via 5.25" bay fan controller)
3x 140mm top exhaust (all three individually controlled via 5.25" bay fan controller)
1x 140mm rear exhaust (individually controlled via 5.25" bay fan controller)
1x 120mm bottom intake (hooked to MoBo, follows CPU temp)
Since i have mid-sized air cooler and it has 2x 120mm fans, this is considered as exhaust as well (hooked to MoBo, follows CPU temp)

By fan placement and size, i'd have negative pressure.
Since i can control almost all my fans individually, i can create whatever pressure i deem fit. E.g if i ramp up my 2x 140 front intake fans (they go up to 2000 RPM and are high CFM/mmH2O fans), while in the same time slowing down my 3x 140mm top and 1x 140mm rear exhaust fans (lowest i can get them is ~500 RPM) - i'd have positive pressure.

With this, you need to figure out if you want to create the negative/neutral/positive pressure with the placement and size of the fans. Or install fans more-or-less random and then use individual control of fans to achieve the negative/neutral/positive pressure.

 

[cameraman]

Too many permutations . I hope once I get my hands on the case it will be easier to plan what, where and how many. I had hoped to order first and have everything on had for a faster build time.

 

[Aeacus]

Without clear goal in mind, it is difficult to plan and build the PC. Just winging it won't make a good result.

But PC airflow rule of thumb is: front & bottom - intake, top & rear - exhaust.
Side fans, usually, aren't best used, since those disrupt the overall airflow path of the PC.